OBJECTIVE: To develop a new method of voiding the bladder in spinal animals by electrical stimulation of the sacral spinal nerves with the "volume conduction" method which can be used for bladder evacuation in human paraplegics. METHODS: 1. In spinal animals under anesthesia, the sacral spinal nerves will be stimulated with the "volume conduction" method in which stimulating electrodes are inserted into the sacral canal in loose contact with sacral nerves. The effectiveness of the electrode placement will be evaluated on the basis of excitation threshold, peak intravesical pressure and the amount of residual urine. "Volume conduction" electrodes will be implanted under anesthesia at the most effective location and the effectiveness and durability of the method will be tested in conscious spinal animals for a long period of time. The criteria employed will include changes in excitation threshold, amount of residual urine and presence or absence of stress signs.